Butachlor is the recognized common name for the active herbicide ingredient 2-chloro-2',6'-diethyl-N-(butoxymethyl)acetanilide. The preparation of this compound and the manner in which it is employed to control the growth of undesired plants are described in U.S. Pat. Nos. 3,442,945 and 3,547,620. In addition, the use of butachlor as a selective herbicide to control the growth of undesired grasses in the presence of rice is described in U.S. Pat. No. 3,663,200. While this latter patent indicates only minimal herbicidal injury to the treated rice plants, it will be noted that the rates of treatment are relatively low.
In the case of upland rice, it is often desirable to use higher rates of the active herbicide ingredient to achieve more rapid or more complete control of the undesired grasses which compete with the crop. Such higher rates, however, can create a significant problem because of the increased level of the detrimental herbicidal effect on the rice crop.